import subprocess

def open_url(url: str):
    if '://' not in url:
        url = 'http://' + url
    if 'example.com' in url:
        return {'success': False, 'message': 'Please do not open example URLs, use a real, existing URL instead.'}
    subprocess.check_call(['xdg-open', url])
    return {'success': True, 'message': 'URL opened in the user browser.'}
